Firefighters are urging smokers to take care when disposing of cigarettes after a fire at a flat on Mapesbury Road in Kilburn.
A small part of a garage roof on the ground floor of a block of flats was damaged by fire. Around 40 people left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade's 999 Control Officers took 13 calls to the blaze.
The Brigade's Fire Investigators believe the fire was caused by the unsafe disposal of a cigarette.
Station Commander Karl Smith who was at the scene said: "On arrival crews were faced with heavy smoke and discovered a small fire in the roof of a garage.
"Fires caused by smoking materials including cigarettes, roll-ups, cigars and pipes, result in more deaths than any other type of fire. Stub cigarettes out properly and always dispose of them carefully.
"Make sure smoking materials are cold before emptying ashtrays. Preferably wet stubs before throwing them into a bin.”
The Brigade was called at 1121 and the fire was under control by 1152. Four fire engines and around 25 firefighters from West Hampstead, Willesden, North Kensington and Paddington fire stations attended the scene.